A disc-type recording and reproducing apparatus that is so configured as to perform a reproducing or a recording operation with an optical pickup while turning a disc-shaped recording medium is widely used. In the above apparatus, the optical pickup is made to access to an optical disc that serves as a disc-shaped recording medium by moving the optical pickup radially to the optical disc while turning the optical disc with a turntable, thereby permitting a predetermined recording or a predetermined reproducing.
In the above apparatus, the optical disc differs in laser beam wavelength of the optical pickup depending on a format of the optical disc. For instance, a laser beam having a wavelength of 780 nm is available for a case of a CD (Compact Disc). On the other hand, the laser beam having the wavelength of 650 nm is required for the case of a DVD (Digital Versatile Disc). Further, the wavelength of the laser beam available for the case of a so-called DVR (Digital Versatile Disc Rewritable) that conforms to a rewritable high-density recording format is 405 nm.
Incidentally, in Japanese Patent No. 2939970, there is disclosed a disc detection apparatus wherein, in a disc player having a sub tray serving to mount a disc available as a recording medium, a main tray serving to hold the sub tray, and a casing serving to house more than one main tray, each main tray has a through hole in a position to match a disc center hole when the sub tray with the disc mounted thereon is held at a stock position supposed to be within the casing, and also, more than one detection hole in positions to be in alignment with an axis extending in a disc loading direction through the through hole of each main tray, and also to be suited to a diameter of the disc, disc detection elements including a pair of light projection section and a light detector are disposed in positions to be in alignment with a perpendicular extending vertically through the through hole of each main tray, and also to put more than one main tray between, and further, the sub tray has a sub tray detection hole in a position to be in alignment with the axis extending in the disc loading direction through the throughhole, permitting a determination on a size and presence or absence of the disc, and further, whether or not the disc is in a predetermined mounting position, by detecting, with the light detector through the detection holes, the through hole, and the sub tray detection hole, light projected from the light projection section at the time of a transfer of the main trays from an open position supposed to be at an outside of the casing to the stock position, or the transfer of the sub tray from the stock position to a play position.
When using the optical pickup capable of emitting the laser beams of the wavelengths suited to all the different formats for the recording and the reproducing applied to the optical discs different in format, a single optical pickup provides a compatible serviceability to the above different types of optical discs.
It is supposed to be practicable that two pieces of lenses, and sections of emitting the laser beams of the wavelengths suited to the above respective for mats are mounted to the single optical pickup enough to be compatibly serviceable, in particular, to the DVR and the DVD/CD, in which case, however, a use of a mounting configuration described the above gives rise to problems that a size of the pickup is so increased as to bring about also a complicated and troublesome adjustment.
In view of the above, to solve the above problems, there is a technology of providing a DVR's optical pickup and a DVD/CD's optical pickup respectively, permitting the above problems to be eliminated by arranging these optical pickups symmetrically about a center of the turntable. In the above technology, the respective optical pickups need to be moved in a radial direction of the disc-shaped recording medium for the recording or the reproducing operation. In order to allow the optical pickups to access the optical pickups to the disc-shaped recording medium while moving the optical pickups radially to the disc-shaped recording medium as described the above, there is provided the tray having an opening that permits the optical pickups to access as described the above in the case where a feed of the disc-shaped recording medium is carried out with the tray.
However, as described the above when forming the opening for moving the optical pickups respectively radially symmetrically about the center of an optical disc mounting position of the tray, so as to access, a large opening is supposed to be given along a length direction of the tray. Thus, the disc-shaped recording medium, in particular, a bare disc is in danger of falling to a lower side of the tray through the large opening described the above. Then, the fallen disc may reach an inside of a drive to cause damages to the optical pickups etc. Even if not causing any damages to the optical pickups etc., a mistaken chucking may cause the damages to a recording surface of the bare disc when the mounted disc is misaligned.
Incidentally, the detection elements disclosed in the above Japanese Patent No. 2939970 are so disposed along a pull-in direction of the sub tray and the main tray as to be in alignment with the center of the sub tray and the main tray. Thus, the above detection elements may carry out a detection of the disc when the mounted disc is misaligned from the pull-indirection, whereas it fails to carry out any detection of the disc when the mounted disc is misaligned sideward from the center, instead of the pull-in direction.
The present invention has been undertaken in view of the above problems, and is intended to provide a disc-type recording and/or reproducing apparatus that is so configured as to, when a large opening is formed on a tray on the grounds of arranging a plurality of optical pickups having different formats so as to be in positions opposite to each other about the center of a turntable, eliminate, surely and effectively, troubles caused by the large opening of the tray, and also a method of judging a disc-shaped recording medium of the disc-type recording and/or reproducing apparatus.